In a variety of machines, particularly engine-powered vehicles, instruments are employed to detect the presence of various undesirable operating conditions, such as overheating of the engine, low oil pressure, low fuel, and the like, and indicators are provided to warn the operator of such conditions. These instruments are often designed to operate in connection with a variety of machine types and are connected to various sensors and switches via a wire harness and/or a communication link. In many applications, these instruments are also connected to electronic control systems such as electronic engine controls, electronic transmission controls, and the like.
The functionality of these electronic controls can only be significantly increased by adding more sensors, and consequently more sensor inputs, to increase the amount of information to be acted upon by the electronic control. The number of sensor inputs, however, is typically limited by the number of wire harness connector pins. To further increase the functionality of the electronic control is therefore limited by the number of wire harness connector pins. The number of inputs can sometimes be increased by adding additional wire harness connectors, however, these connectors are bulky and expensive. It is therefore advantageous to provide additional information to the electronic control while not increasing the number of harness connector pins required.
Since the instrument for displaying information may be used in connection with many different machines, it is advantageous for the instruments to be as flexible as possible. Lower costs will be achieved and less warehousing space will be required if a single instrument is manufactured which can be used in many different applications and in connection with many different electronic controls.
These instruments also have a limited number of displays for indicating parameter levels. To increase the amount of data displayed usually requires an increased number of displays. While feasible in some applications, the addition of more displays is often prohibitively expensive and is limited by space availability. It is therefore advantageous to increase the amount of information that may be indicated by any given display.
In some cases it is also advantageous to display in digital form a number representative of the level of a parameter in engineering units. This may be important for sensor diagnostic purposes or to more precisely monitor a parameter.
The present invention is directed to overcoming one or more of the problems set forth above.